A FORENSIC paediatrician who examined alleged murder victim Matthew Baxter has told a court the baby collapsed after suffering head trauma.
Matthew's father Nicholas Baxter has pleaded not guilty to murder and is on trial in Townsville Supreme Court.
Baxter allegedly shook or struck Matthew on November 3, 2011, causing brain bleeding and swelling and retinal haemorrhages.
Children's Health Queensland's Dr Catherine Skellern said she was tasked to investigate the cause of Matthew's death, and noted rib fractures in chest X-rays and post-mortem skeletal surveys.
"Importantly they weren't fresh, they had very clearly substantially preceded the time that he'd presented with his collapse and head injury," she said. Two were to Matthew's back, she said, and were at least three weeks old.
"The mechanism is very specific, because it actually requires someone to put their hands around the baby and ... chest encirclement and compression are the necessary mechanisms," she said.
Dr Skellern said Matthew had 15 fractures to his front.
"Most of the time rib fractures are not something that any person looking after a baby would actually know that a baby has," she said. "For the most part, rib fractures are only diagnosed when we X-ray babies."
Dr Skellern said Matthew's brain swelling and bleeding was likely caused by trauma.
Crown prosecutor Nathan Crane asked whether, if there was impact to a child's head, you would always see an injury.
"No, in fact it's not necessarily what I would expect to see," Dr Skellern said.
"Because there isn't much in the way of hair, scalp, the bone is quite thin, the transmission of contact force to the head would be transmitted to the brain itself, to cause the brain to rotate inside the skull and generate injury to the brain itself."
Defence barrister Lincoln Crowley said Dr Skellern wrote in her report that there was controversy in medical literature about whether non-impact shaking could cause subdural (brain) haemorrhages.
"There is, as you can imagine, a wide range of views on this matter, and that's been subject to ... research," she said.
"My view is that traumatic shaking, even without direct impact to the head can cause injuries of the type Matthew had."
Dr Skellern said Matthew did not have the bone condition rickets, a bleeding or clotting disorder or an infection.
Mr Crowley's case is that Matthew died from medical issues.
The trial continues.